Looks to me like it might be DeaDBeeF.

I first used fedi from Twidere on my phone, but later switched to Fedilab for some reason. It might've been that Fedilab had implemented rich text post support, and since I was using Pleroma this was a distinctive feature for me. I'm a bit curious if Twidere has changed or improved much in this time, but I think a sort of "happy accident" of me switching away from it is that I'm even less likely to browse Twitter during my idle time.